Ventilating machine

ABSTRACT

A VENTILATION MACHINE PARTICULARLY FOR SURGICAL USE ALLOWS A FULL FACILITY FOR ADJUSTMENT OF INHALATION AND EXHALATION DURATION AND PRESSURE. THE MACHINE IS ACTUATED BY AN OVER-CENTRE TOGGLE MECHANISM RESPONSIVE TO THE VOLUME OF A CONTROL CHAMBER. THE LATTER IS CONNECTED TO A CHAMBER CONTAINING A BAG FROM WHICH GAS IS FORCED TO THE USER.

Nov. 23, 1971 Filed July 3, 1969 United States Patent 3,621,842 VENTILATING MACHINE Roger E. W. Manley, Chesham, England, assignor to Blease Medical Equipment Limited, Deausway, Chesham, England Filed July 3, 1969, Ser. No. 838,996 Claims priority, application Great Britain, July 5, 1969, 32,259/69 Int. Cl. A61m 16/00 US. Cl. 128145.6 9 Claims ABSTRACT OF THE DISCLOSURE A ventilation machine particularly for surgical use allows a full facility for adjustment of inhalation and exhalation duration and pressure. The machine is actuated by an over-centre toggle mechanism responsive to the volume of a control chamber. The latter is connected to a chamber containing a bag from which gas is forced to the user.

This invention relates to a ventilation machine, and in particular to a ventilation machine for use in hospital operating theatres for supplying air, gas or air-gas mixtures to a user who will normally be a patient undergoing surgery. In this specification, the term gas will be used to include air alone, oxygen alone, and air-gas mixtures or mixtures of oxygen with another gas or gases for example an anaesthetic gas.

It is an object of the invention to provide a ventilation machine driven by gas pressure and requiring no other external power.

It is another object of the invention to provide such a machine which is of reliable design which will require a minimum of maintenance.

It is a further object of the invention to provide such a machine in which the patient or other user can be assisted to exhale by suction, or can be required to exhale against a positive pressure.

It is yet another object of the invention to provide a simple volume-cycled machine facilitating the making of a large number of adjustments by the anaesthetist, for example, inspiratory and expiratory pressure, and duration of inhalation and exhalation phases.

According to the present invention in its general aspect, there is provided a ventilation machine comprising a variable volume chamber adapted to be connected to a face mask for a user and to be contracted to force gas to the user by pressure of gas within a variable volume control chamber, an over-centre toggle mechanism responsive to the control chamber volume and arranged to actuate a first valve which can allow gas into the control chamber and a second valve which can be actuated to allow exit of gas from the control chamber.

The second valve may be actuated in response to closure of the first valve.

Advantageously, a bleed orifice in the control chamber is provided to allow slow escape of gas from the control chamber. This, as will be seen, permits alteration of the duration of the inspiration phase. For this purpose, the bleed orifice is of adjustable size.

The over-centre toggle mechanism may be connected to a flexible diaphragm partially bounding the variable volume control chamber. A further chamber may be located on the opposite side of the flexible diaphragm from the over-centre toggle mechanism, and the said further chamber may have a bleed orifice therefrom. The pressure applied within this further chamber has a biasing effect on the flexible diaphragm, and by adjusting the pressure in the further chamber, it is possible to permit selection of the duration of the users expiratory phase.

The flexible diaphragm is preferably biassed inwardly relative to the control chamber by a spring. The spring may be adjustably mounted so that the force exerted by it on the flexible diaphragm can be varied. This allows adjustment of the inspiratory pressure.

The invention will be better understood from the following particular description of an illustrative embodiment thereof, given with reference to the accompanying drawing, which is a diagrammatic representation of one embodiment of apparatus according to the invention.

The illustrated ventilation machine comprises a variable volume chamber 10 constituted by a bellows located within a glass jar 12, the interior of the jar being connected by a pipe 14 to a variable volume control chamber 16. This chamber is bounded on one side by a flexible diaphragm 18. The control chamber 16 has a bleed orifice 20 therefrom constituted by a needle valve, and the casing of control chamber 16 is contiguous with the casing of a further chamber 22. This chamber 22 is also bounded by the diaphragm 18. A compression spring 24 is located between the flexible diaphragm 18 and an adjustable mounting 26. The adjustable mounting 26 may for example comprise an abutment located within a threaded tubular part 28 of the wall of the chamber 22, in such a way that the abutment can be screwed inwardly or outwardly by an externally-applied tool. The chamber 22 has a bleed orifice 30 therefrom, also constituted by an adjustable needle valve.

The control chamber 16 has a first, or gas entry, valve 34 having a valve member 36. The valve member 36 is mounted on pivoted lever 38 which in conjunction with a spring 40 constitutes an over-centre toggle mechanism. The spring is connected to a rod 44 secured to the flexible diaphragm 1-8 and the lever 38 is pivoted at 42.

The control chamber 16 has a second, or gas exit, valve 50 in the wall thereof, the said valve having a valve member 52 and being biassed to a closed condition by a compression spring 54. Its valve member 52 is secured to a rod 56 whose other end is secured to a diaphragm 58 bounding a small cylindrical closed volume 60.

The ventilation machine includes a gas supply tube 64 which branches into sections 66 and 68. Section 66 leads to a double-Venturi arrangement which Will be shortly described, and section 68 leads via a needle valve 70 (which is used to adjust the flow rate) to a first branch 72 leading to the first valve 34 and a second branch 74 leading to the interior of the cylindrical volume 60. Thus when the valve 34 is open gas is supplied from a pump, not shown, but connected to tube 64, to the interior of the control chamber 16. When the valve 34 is closed gas is supplied to the interior of the cylindrical volume 60.

The roof of the glass jar 12 is rigid and serves to mount the bellows 10, and has an orifice therein by which the interior of the bellows 10 is connected via a tube 82. to a face mask, diagrammatically indicated at 84, for the user. The bellows 10 is normally held expanded by the weight of a plate 91 forming its bottom wall. The face mask 84 is also connected, via a tube 86, to a bacterial filter 88, which may be dispensed with if desired, and then to an expiratory valve 90. This valve is a non-return valve and allows expiration of air through tube 86 but does not allow inspiration of air through that tube. In a similar way, the tube 82 contains a non-return valve 83 assuring that the user can inhale the contents of the bellows 10 but cannot exhale into the bellows 10. A tube 85 is connected to the tube 82 and contains a non-return valve 87. The end 89 of the tube is open to the atmosphere. This arrangement allows air to enter the bellows 10 when they expand. This expansion occurs due to the weight of the plate 91 when the pressure is removed from the interior of the glass jar 12.

Exhalation is assisted by the double-Venturi system generally indicated at 92. This system includes two nozzles, 94, and 96, directed at right angles to one another and each extending into a surrounding tube narrowed as indicated at 98 and 100 respectively to provide a Venturi effect. The nozzle 94 is supplied via pipe 192 from an expiration pressure adjusting tap 104, and the nozzle 96 is supplied from the same tap via a tube 106. The tap 104 is supplied from branch section 66 via a flow-regulating needle valve 108. In normal use, the setting of needle valve 108 is such that the flow through the valve 70 provides sufiicient pressure in the line 74 to overcome the spring 54 when the valve 34 is closed. The normal setting of the valve 70 is of course consistent with the foregoing requirement and with the requirement that the maximum flow rate through needle valve 70 is less than the flow rate through the valve 34 when open. This ensuures that when the valve 34 is open, pressure in the control chamber cannot build up, so that the spring 54 holds the valve 50 closed.

With this arrangement it will be seen that if the valve 104 is altered so that gas is solely supplied along tube 106, then the expiratory pressure applied to the patient will be at its minimum value. In fact a suction will be so applied. Likewise, if the tap 104 is turned so that all the air supplied along branch section 66 is fed through tube 102, and none through tube 106, the suction effect applied to the face mask will be minimal and in exhaling, the user will have to overcome a positive pressure opposing such exhalation.

The operation of the apparatus will now be described.

Starting for the sake of example during the inspiratory phase, the first valve 34 is open (as shown in the drawing) with the valve member 36 being urged against a suitable stop 37 by the tension spring 40. Gas is being supplied (a) from the pump via tubes 64, 68 and 72 and (b) from the nozzles 94 and 96 to the interior of the control chamber 16 and thence to the interior of the chamber 12. It will be understood that non-return valve 90 is closed. The bellows is therefore compressed, and the gas therein is expelled via tube 82 and 83 to be inhaled by the user. While this occurs, the gas exit valve 50 is closed and pressure gradually builds up within the control chamber 16 at a rate determined by the rate of leaking of gas through bleed orifice 20 out of the chamber 16. The build-up of pressure can be made slower by opening the adjustable orifice 20. As the pressure increases in control chamber 16, the flexible diaphragm is distended and therefore moves in a direction to the right as seen in the diagrammatic drawing against the spring 24 and 1 against the pressure within the further chamber 22. This draws the rod 44 to the right, to a position where it trips the over-centre toggle mechanism 36, 38, 40, 42 thereby pivoting the lever 38 in an anti-clockwise direction and closing the valve member 36 to the body of the valve 34,

thereby closing the gas entry valve 34. The gas supplied along tube 68 then flows via tube 74 to the cylindrical chamber 60, distends the diaphragm 58, and lifts the valve member 52 to open gas exit valve 50. Gas then quickly escapes from the interior of the control chamber 16 through the valve 50, and with the reduction in pressure within chambers 12 and 16 the bellows are free to assume their expanded condition. An arrangement, not shown, is provided to ensure that in so doing the bellows 10 fill with air or from atmosphere with oxygen or other gas as may be required by the medical or surgical staff in charge of the machine. The shutting of valve 34 marks the end of the inspiratory phase, and the expiratory phase commences. During this phase, air is sucked from the user via tube 86, filter 88, expiratory valve 90, through the action of the Venturi system 92. For convenience, though this is not an inherent feature of the invention, the exhaled gas is passed into the interior of control chamber 16 as illustrated.

With the reduction in pressure within the control chamber 16, the diaphragm 18 moves under the action of the spring 24 and pressure within further chamber 22 in a direction to the left, until the rod 44 is thereby moved a distance such that the over-centre toggle mechanism 36, 38, 40 42 is again triggered. When this occurs, the first valve 34 is opened and the inspiratory phase again commences. It will be seen that the sequence of events described above will occur repeatedly.

By adjusting the spring abutment 26 the inspiratory pressure may be adjusted, and by adjusting the bleed orifice 30 the rate at which the diaphragm 18 moves to the right can be altered, thereby adjusting the duration of the expiratory phase. By adjusting the bleed orifice 20, the rate at which pressure builds up within the control chamber 16 can be selected, thereby allowing alteration of the duration of the inspiratory phase. By suitable adjustment of the tap 104, the expiratory suction or pressure applied to the user can be varied.

Among the advantages of the machine described herein are that it can be operated with a relatively simple pump supplying compressed air or gas at a pressure of only about 2-3 lbs. per square inch, and that the simplicity of the cycling mechanism is conducive to durability and easy maintenance.

The specific embodiments described and illustrated herein is of course exemplary and not limitative and modifications will occur to one skilled in the art.

I claim:

1. A ventilation machine comprising:

(a) a first variable volume chamber having a moveable wall;

(b) a second variable volume chamber in communication with said first variable volume chamber, associated in such a manner that changes in the pressure of said first variable volume chamber produce corresponding changes in the volume of said second variable volume chamber;

(c) a face mask connected to said second variable chamber by means of which a user can breathe;

(d) A tube connected at one end to said face mask and at the other end to said first variable volume chamber, said tube having a pair of narrowed portions in the interior thereof;

(e) A pair of nozzles disposed within the tube, each nozzle cooperating with a narrowed portion to provide a venture effect, said nozzles oriented in different directions in the tube so that one of the nozzles provides suction tending to draw gas from the face mask and the other provides suction tending to draw gas from the interior of said first variable volume chamber, said nozzles arranged to allow adjustment of the expiratory pressure applied to the user;;

(f) means for connecting said nozzles to a pressurized gas source;

(g) an over center multi-position toggle mechanism responsive to pressure variations in said first chamber;

(h) a first valve connected to the toggle mechanism opening and closing in response to the movement of the toggle mechanism for controlling the entry of gas into said first variable volume chamber;

'(i) means for connecting said valve to a pressurized gas source; and

(j) an exit valve in the first variable volume chamber responsive to pressure in said first chamber.

2. A machine as claimed in claim 1, wherein the exit valve in said first chamber is biased in a closed position and opens in response to the closing of said first valve.

3. A machine as in claim 1, wherein said first chamber has a bleed orifice.

4. A machine according to claim 3, wherein said bleed orifice is adjustable in order to vary the duration of the users inhalation phase.

5. A machine as in claim 1, wherein the moveable wall in said first variable volume chamber partly defines a third variable volume chamber having an adjustable bleed orifice in order to provide a selected rate of reduction of pressure in said third chamber to permit selection of the duration of the users expiratory phase.

6. A machine according to claim 5, wherein the moveable wall is a flexible diaphragm including a spring means biasing the diaphragm inwardly relative to the first variable volume control chamber.

7. A machine according to claim 6, wherein said spring means includes means for adjusting the force of the spring.

8. A machine according to claim 1, wherein the nozzles are directed in perpendicular directions.

9. A machine according to claim 5, wherein said over center multi-position toggle mechanism is connected to and operated by the movement of the moveable wall in said first variable volume chamber.

References Cited UNITED STATES PATENTS 2,766,753 10/1956 Koch et al 128l45.8

10 RICHARD A. GAUDET, Primary Examiner J. B. MITCHELL, Assistant Examiner UNITED'STATES PATENT DFFICE" CERTIFICATE OF CORRECTION Patent No. 3, 621, 842' Dated November 23, 1971 Inventor(s) ROGER W. MANLEY' It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Column 1, line 7, correct to read Claims priority,

application Great Britain, July 5, 1968,

Signed and sealed this 6th day of June 1972.

(SEAL) Attest:

EDWARD M.FLETCHER, JR. ROBERT GO'IISCHALK Attesting Officer Commissioner of Patents Powm uscoMM-Dc 60376-P69 9 1,5. GOVERNMENY PHINYING OFFICE 9'9 0-356-33. 

